1. Field of the Invention
The field of the invention generally relates to catheters and balloons, specifically for percutaneously producing hemostasis in peripheral arteries
2. Prior Art
Prior Art References:
Pub. No.Date1st author name0195457October 2003LaFontaine, et al0073238April 2004Makower0116946June 2004Goldsteen, et al0111733May 2006ShriverMethods for Restoring Blood Flow in Arteries
Revascularization restores blood flow in arteries by either going around or going through the occlusion restricting the flow. A bypass graft is the means of taking a supply of blood proximal to the occlusion site and going around the occlusion to deliver the blood to a site distal to the occlusion. At the present time surgery is the only approved method for placing a bypass graft. Percutaneous methods of revascularization go through rather than around the occlusion. Percutaneous entry is accomplished by a standard procedure of puncturing the skin with a hollow needle where the artery is large and close to the skin, commonly the femoral artery in the groin. A guiding catheter is inserted at the entry site and advanced toward coronary arteries or peripheral arteries, whichever are occluded. A common method of opening an occlusion is advancing a balloon on a catheter through the guiding catheter and into the occlusion where the balloon is inflated. This pushes open the occluded section of the artery and the balloon is deflated and removed. A newer method is to place a bare or drug eluting stent around the balloon to keep the occluded area propped open after the balloon is removed. Another option is advancing any one of many devices for removing occlusions through the guiding catheter to the site of occlusion. There are mechanical, electrical, chemical and cryogenic means of removal, chosen for the nature of the occlusion, e.g. calcified or thrombus-filled.
Most Effective Method
Of all the available revascularization methods the bypass graft is known to be most effective. But since surgery is presently the only procedure for placing bypass grafts, the less effective percutaneous methods are preferred since they involve almost none of the trauma, pain, risk, and long recovery time of surgery. The surgical trauma is not from connecting the ends of the bypass graft to the artery with tiny sutures in small arteriotomies. That is minor surgery though it requires high skill to place a suture a minute. The trauma is from gaining access to the arteries surgically, producing hemostasis, and harvesting a vein to use as the bypass graft. To gain access to coronary arteries the chest must be cleaved in two and ribs pulled back to expose the heart. The bypass graft is connected to the aorta as the source of blood for delivery through the bypass graft around the occlusion to the coronary artery distal to the occlusion. The aorta is usually clamped shut to achieve hemostasis. And since all the oxygenated blood from the heart is delivered through the aorta, it can't be clamped shut until the heart is stopped and a mechanical heart substituted to oxygenate and pump the blood to the body. Surgeons must work fast to finish suturing two or three bypass grafts in place within an hour, because risk goes up for longer time on the mechanical pump. Gaining access to peripheral arteries produces even higher mortality and morbidity than does gaining access to coronary arteries. Generally the surgical bypass patient is in intensive care for a day, a week in hospital and has many months of painful recovery. The patient treated by a percutaneous method is likely to be home in a day or so with essentially no pain. With this major difference in the effects of percutaneous and surgical treatment, it is not surprising that the less effective percutaneous treatments are selected about four times as often as the more effective bypass grafts.
Placing Bypass Grafts Percutaneously
It has long been obvious that if access for placing bypass grafts could be percutaneous, the graft's long-term effectiveness could be obtained without the undesirable surgical trauma. There have been four inventions published by the USPTO for devices to place bypass grafts percutaneously. Since coronary artery disease is the number one killer it is not surprising that all four use coronary arteries for their preferred embodiment. None specifically addresses unique conditions in peripheral arteries but each generally claims application to all vessels of the body. The devices described in these four inventions share certain objects that are common to all methods of placing bypass grafts. Two of these objects are making arteriotomies and achieving hemostasis. But the means of accomplishing these objects in a coronary situation are not applicable to peripheral artery situations because of critical differences in the two situations. One difference is that coronary arteries are in a fluid medium and the peripheral arteries in a tissue medium. A second difference is that the aorta at the coronary site is more than four times the diameter of a peripheral artery. A third difference is that blood in the aorta cannot be stopped without stopping the heart but this is not the case with a peripheral artery. Because of these differences the means provided in the previous inventions for achieving the objects of hemostasis and arteriotomies in a coronary application will not achieve those same objects in a peripheral artery application and/or are not needed in a peripheral artery situation. None of the four inventions has been shown to achieve the objects in the coronary situation for which they were designed as none have received the required US Federal Drug Agency approval for their use. No literature has been found that describes any attempts to apply them in peripheral arteries. The devices are discussed here in terms of whether the means they describe for achieving hemostasis are relevant as prior art to the means used by the present invention.
Mackower device In the invention by Mackower, the coronary vein is utilized as the bypass graft. The coronary vein runs parallel to the coronary artery and only a few millimeters from it on the surface of the heart within the liquid-filled pericardium. This short distance, with pericardial fluid between the vein and artery, and no involvement of the aorta, makes it possible for the Mackower device to use a sharp, short hollow tube to pierce the artery and enter the vein. This achieves hemostasis because the walls of both artery and vein are distended to allow the tube to pass while pressing tightly around the tube. The aorta is not the source of blood so the heart does not need to be stopped. A flexible seal is then pushed through the tube and allowed to expand in the lumen of the vein. The seal acts like an opened umbrella in the vein to prevent blood from escaping through the venous arteriotomy when the tube is withdrawn from the vein. The hollow tube is withdrawn into the artery where the other end of the seal is released. Thus the vein and artery are drawn toward each other in a side-to-side anastomosis. The vein and artery are connected on the other side of the occlusion in the same way. Incisions are then made in the chest to tie off the vein on either side of the two connections thus ending its function as a vein and making it a bypass graft. It may be noted that the vein is not turned around in this procedure. When sapheneous veins are used as coronary bypass grafts, they are turned around so the blood flows in the same direction it flowed when they were veins. It is reported in the literature that the coronary vein failed as a bypass graft. This may be because the vein was not turned around or because the coronary vein is too small to function as an artery or both, or for some other reasons not described. Whatever the reason, there are no means involved in the present invention that have any relationship to the means used in the Mackower device. The similarity is entirely in terms of objects, not prior art means.
LaFontaine device In the invention by La Fontaine, et al., hemostasis is achieved by an isolation device that applies a vacuum to the site of an arteriotomy. The patent application says this is to remove “blood from the region of the wall of the aorta where the incision is to be made and preclude additional blood flow from entering that area. Thus, a clear working space is created adjacent to the wall of the aorta . . . such that an incision can be made without a significant amount of blood being released from the aorta . . . through the incision.” Whether or not this works in a coronary situation is not known. No report has been found in the literature of it being tried in a coronary or a peripheral artery situation. But the means described in the present invention for achieving hemostasis does not require a vacuum, but is accomplished by inflating one or more balloons in the peripheral artery to stop the flow of blood and thus create hemostasis. The present invention has one embodiment where the hemostatic guiding catheter carries a vacuum after hemostasis is achieved. A vacuum is used in medicine for many objects and in this case it is to pull tissue toward a cutting edge to accomplish an arteriotomy. There is no prior art described in the La Fontaine invention to compare with the art in the present invention.
Goldsteen device The invention by Goldsteen, et al., creates local hemostasis in the aorta around an arteriotomy as the opening is made. An arteriotomy is started with a stylet wire that makes an initial opening in the aorta. The means of increasing this tiny opening to the size needed for connecting to a bypass graft is described as using successively larger diameter sheaths to twist through the initial small opening. The assumption is that the aorta wall will remain in such close contact with the sheaths that no blood will escape around them. The sheaths are delivered through a guiding catheter that must be held against the aorta wall at a 90 degree angle. After an arteriotomy of the size needed is achieved, the guiding catheter is advanced through the opening. An annular balloon around the distal end of the guiding catheter is then inflated on the adventitial side of the aorta. This balloon presses against an annular balloon inside the aorta to squeeze the edge of the opening in the aorta between them. The Goldsteen patent application says the close spacing and resilient bias of the balloons toward each other helps to anchor the catheter to the aorta—and create hemostasis. It is not known if the Goldsteen device accomplishes the object of hemostasis in the aorta as there are no reports of trials in the literature. But it is known that the Goldsteen device entered trials several years ago but has not been approved for use by the US Food and Drug Agency. It is clear that the Goldsteen device requires the fluid medium surrounding the coronary aorta in which to open a balloon on the adventitial side of the aorta. Even if an arteriotomy could be accomplished in a peripheral artery by the Goldsteen device, the peripheral artery is surrounded by tissue and no means is provided in the Goldsteen device for entering this tissue or removing it in order to open a balloon. Also, since the Goldsteen device offers no other means of moving the catheter it has to be assumed it is moved by an operator pushing on the proximal end. This is routinely done with a catheter in the aorta to advance balloons and stents to occlusion sites. This is not a problem in the aorta which is about 36 mm in diameter and the guiding catheter is about 4 mm. This is a sufficient distance to turn the distal end of the guiding catheter 90 degrees from its longitudinal axis. The shape of the guiding catheter typically used to do this is that of a hockey stick. This places the distal end of the catheter at 90 degrees with respect to the aorta wall. It is not possible to make a 90 degree turn in a peripheral artery of 6-9 mm in diameter with a catheter of 4-7 mm in diameter. Thus sheaths cannot be delivered for twisting through the peripheral artery wall at an angle of 90 degrees with respect to the wall, as the Goldsteen device requires. The present invention provides the distal opening in the side of the catheter wall at an angle of 90 degrees to the longitudinal axis of the catheter and also provides balloons that apply force vectors to push the hemostatic guiding catheter toward the wall or through an opening in the wall. The present invention creates hemostasis by creating a barrier to the flow of blood in a peripheral artery by inflating one or more annular balloons around the guiding catheter inside the artery lumen. The present provides the means of placing a balloon on the adventitial side but after hemostasis is established. The means described in the Goldsteen device for hemostasis are not needed in the peripheral artery and cannot be applied because the artery is too small in circumference and the Goldsteen device provides no means of removing tissue surrounding the peripheral artery in order to open a balloon. Thus the Goldsteen device provides no prior art for comparison to the means used by the present invention for use in a peripheral artery application.
Shriver device The invention by Shriver uses a guiding catheter with two annular balloons on the distal end for use in coronary applications. The guiding catheter also has a double wall with one divider to provide two conduits for inflation fluid for the annular balloons. The catheter shape is described as being like those for balloon angioplasty such as “hockey stick” for turning the catheter across the aorta at a 90 degree angle and lodge against the side opposite the point of turn. The balloon and guiding catheter must be at a 90 degree angle to be effective. The catheter is placed at 90 degrees to the aorta wall and the proximal balloon is inflated before the opening is made in the aorta wall. This approach to the artery wall cannot be achieved in a peripheral artery because the peripheral artery is not large enough for the catheter to be turned 90 degrees. A cutting device is then lodged in the guiding catheter and the guiding catheter pushes the cutting device through the aorta wall. The assumption is that blood will not escape around the guiding/clamping catheter before an annular balloon can be inflated on the adventitial side of the aorta to clamp the artery wall between that balloon and a balloon inflated in the lumen of the artery. Even if that assumption is true the prior art cutting element has only the force vector in line with the longitudinal axis of the aorta to push against the aorta wall at a 90 degree angle and that is not possible in the peripheral artery situation. And no means are provided in the Shriver device for removing tissue on the adventitial side of the artery in order to open a balloon. Thus, the elements of the prior art Shriver device for making an arteriotomy and achieving hemostasis in the fluid environment and large aorta of a coronary application cannot achieve the same objects in a peripheral artery situation so they are not prior art with respect to the present invention. There are two inflation fluid conduits described in the prior Shriver device that are modified in one embodiment of the present invention to provide a larger number of conduits. Whether or not this is an obvious difference with respect to the prior art is not known. But it is clear that the Shriver device does not provide prior art for achieving hemostasis in peripheral arteries.
3. Objects and Advantages
The object is to produce hemostasis at a pre-selected site in a peripheral artery by percutaneous means that also provide a closed pathway for guiding other devices to the artery wall at this site. The advantages over prior art are:
1. Providing a hemostatic guiding catheter slightly smaller than the diameter of the artery in which it is used that bends at an angle from the longitudinal axis toward the artery wall thus stopping the flow of blood through most of the artery area and deflecting any longitudinal element being guided through the hemostatic guiding catheter toward the artery wall.
2. Providing a hemostatic guiding catheter with a distal opening in the shape produced by intersecting the bent distal end with a cylinder the circumference of the artery in which the hemostatic guiding catheter is intended for use, thus creating a distal opening with edge contiguous with the artery wall.
3. Providing a hemostatic guiding catheter with one or more annular balloons near the distal end that inflate to produce a barrier between the hemostatic guiding catheter and the artery wall to obstruct the flow of blood in the artery, thus creating hemostasis.
4. Providing a hemostatic guiding catheter with a smooth, continuous, hard, inner surface that will smoothly deflect longitudinal elements such as a steerable piercing guidewire, an anchor wire, a delivery catheter, and excision/incision cup, and also provide a suitable conduit for a vacuum applied at the proximal end to the distal opening.
5. Providing one or more annular balloons near the distal end of the hemostatic guiding catheter for additional purchase on the artery wall thus preventing slippage of the hemostatic guiding catheter and distributing the pressure on the artery so the pressure is not concentrated on an artery with reduced elasticity.
6. Providing a hemostatic guiding catheter with one or more annular balloons that are biased to inflate more on the side away from the distal opening than on the side of the distal opening to provide lateral movement of the guiding catheter in an artery and to push the hemostatic guiding catheter tightly against the distal opening.
7. Providing a hemostatic guiding catheter with annular balloons shaped to extend from their line of attachment over the guiding catheter to which they are attached, like a foreskin over a penis enabling adjacent annular balloons to push against each other to increase the pressure produced by each and to enable the balloons to roll back as the catheter moves forward. This allows a short forward motion as through an arteriotomy or a forward-and-back sawing motion while the foreskin shaped balloon(s) maintain(s) hemostasis through contact with the wall of the artery. Either of these effects can be useful in connection with other elements of percutaneous devices for placing bypass grafts.